The present invention relates to rotary compressors. More specifically, the present invention relates to a rotary compressor having a sliding vane which minimizes noise, and additionally, minimizes wear to the vane-roller interface due to improved lubrication.
A rotary type of compressor as commonly used for refrigerators and air conditioners often generates high frequency noise. Indeed, some refrigerators use rotary compressors which show a strong almost pure-tone noise of about 4 khZ.
Lubricant degradation caused by excessive heat generated at the vane-rolling piston contact occurs in such rotary compressors due to friction. This often results in a total loss of function and is a severe problem. The noise, friction, and lubrication problems are believed to be closely related.
Prior vane structures have tended to clump lubricant on one side of the vane, thereby causing an uneven distribution of lubricant. It should be noted that lubricant is often included in the refrigerant and is operable to coat various working surfaces of a rotary compressor.
Various methods of reducing rotary compressor noise have previously been considered.
One approach is to redesign the casing of the rotary compressor so as to reduce the sound radiation from it. The noise heard by the human ear results from the vibration of the casing which encloses the whole compressor structure. Modifying the sound radiation pattern is necessary for this approach. Theradiation can be modified by changing the bending rigidity of the compressor, i.e., changing the casing thickness or adding stiffness to the casing. However, redesigning the casing is relatively expensive and is therefore undesirable.
Another way of attenuating the compressor noise is by controlling the compressor gas spectrum. Any resonator type of device built into the discharge port works as a mechanical filter. This may adversely effect the compressor efficiency depending on the structure of the resonator.
Other attempts to reduce the high frequency noise have included changes in orifice design, clearances, and root radii. These changes have been only partially successful and are somewhat disadvantageous in that they often reduce the efficiency of the compressor.
Although the above approaches at noise reduction have been somewhat useful, there remains a need for significantly reducing the noise from a rotary compressor without reducing the efficiency of the compressor. Further, there is a somewhat related need to decrease friction and to avoid lubricant degradation.